These ancient sunken lanes were naturally tunneled into the soft ground by countless footsteps.

Football field-sized microalgae production tanks on the Hawaiian coast create a stunning view from space.

Thousands of acres of beautiful wild landscape in the Great Basin.

A collection of heirloom roses tucked in a spectacularly beautiful botanical garden on Lake Atitlan.

An impressive century-old, to-scale topographical map of Guatemala.

On the highest peak in the Harz Mountains, science and the occult faced off in a failed attempt to turn a goat into a boy.

The spot where the namesake of the Douglas fir met his mysterious end on a Hawaiian volcano.

The world's longest and deepest train tunnel.

Berlin's beloved bear is immortalized at the Museum für Naturkunde.

A 24-hour vending machine restocked daily with homemade full-sized pecan pies.

An abandoned beach resort in Normandy reclaimed by artists.

A wunderkammer of exoticism immortalized by Tom Waits.

The iconic D.C. restaurant where the Cuban Missile Crisis was negotiated, now a Walgreens.

A monument stands to the famous suffragist who penned the declaration for women's equal rights, including the right to vote.

The nation's second-ever First Lady urged the founding fathers to "remember the ladies."

The gravestone of the suffragist leader attracted extra visitors during the 2016 election.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

This hidden stream beneath Indianapolis makes an appearance in the best-selling novel "Underground Airlines."

A centuries-old shrine where Indians pray for U.S. visas.

This 19th century granite fortification is one of the most well preserved forts in New England.

These 20-foot jaw bones honor a time when the leviathan bones were a sign that whalers survived the hunt.

The recovered bones of martyrs slaughtered during The Terror are on display in this church crypt.